Moulting replaces worn feathers, usually once or twice every year for most birds.

The longer version

Feathers are dead tissue, so damage never repairs, it accumulates. Moulting drops old feathers and grows replacements from the same follicle. Because a bird must keep flying and staying warm, the process is staged rather than all at once, and flight feathers are usually shed in matched pairs so the wings stay balanced.

Timing is fitted around the rest of the year. Most birds moult after breeding, when food is still plentiful and migration has not begun, and some change appearance as well, wearing duller plumage outside the breeding season. Waterfowl are unusual in dropping all flight feathers at once and being briefly flightless.

Where this entry sits

Here you will find feathered trivia about flight, migration, nests, eggs, and the songs birds sing. Expect short surprising facts on penguins, owls, hummingbirds, and other familiar birds from gardens, forests, wetlands, and distant coastlines. The full list sits on the Birds page, where every entry is listed in order.